Apparatus for cleaning electrical contacts



April 8, 1969 M. KANTOR APPARATUS FOR CLEANING ELECTRICAL CONTACTS FiledNov. 30, 1964 Sheet INVENIOR dommwmz u 5926b Em:

MISHA I. KANTOR ATTORNEYS April 8, 1969 M. I. KANTOR 3,436,735

' APPARATUS FOR CLEANING ELECTRICAL CONTACTS Filed. Nev. so, 1964 Sheet2 of 3 AIR,\MPRCT MATIRUQ. P!

INVENTOR MISHA l. KANTO R 6| 5 I BY ATTORNEYS Apnl'8, 1969 M. I. KANTORAPPARATUS FOR CLEANING ELECTRICAL CONTACTS Filed Nov. 50, 1964 SheetINVENTOR MISHA l. KANTOR ATTORNEYS 3,436,785 Patented Apr. 8, 19693,436,785 APPARATUS FOR LEANING ELECTRICAL CONTACTS Misha I. Kantor,Orlando, F121,, assignor to Radiation Incorporated, Melbourne, Fla., acorporation of Florida Filed Nov. 30, 1964, Ser. No. 414,692 Int. Cl.A471 5/38 US. Cl. -301 3 Claims ABSTRACT OF THE DISCLOSURE Cleaning ofelectrical contacts is accomplished by subjecting the contacts toalternate blasts of cooling air and non-abrasive impact material.Brushing of the contacts is performed concurrently with the impactcleaning operation to dislodge residue and impact material. Thedislodged deposits are collected and removed from the region occupied bythe contacts by use of a vacuum exhaust scavenger system.

The present invention relates generally to cleaning systems forelectrical contacts, and more particularly, to cyclic impact cleaningand cooling systems for multistylus assemblies and other electricalcontact assemblies wherein the assemblies or contacts are loacted inclose proximity to moving machine parts.

In certain exemplary embodiments, the cyclic cooling and cleaning systemof the present invention is used in connection with multistylusassemblies for electrosensitive printers. In the following description,it will be understood, however, that systems in accordance with thepresent invention may be employed wherever it is necessary or desirableto clean a plurality of delicate electrical contacts, which are subjectto build-ups of residue and/ or to high temperature operation, and whichmay require the eflicient collection and removal of impact material usedin the cleaning process and dislodged residue to prevent interferencewith adjacent operating machine parts.

The multiple stylus assembly of an electrosensitive printer or recorderis exemplary of equipment in which the need for an efficient system ofcleaning is of paramount importance. In operation, the printer suppliesa recording or chart of desired information by virtue of the marking ofan electro-sensitive medium, generally a sheet, by the styli. Morespecifically, the multiple stylus assembly carries electrical current tothe electro-sensitive medium on which it is superposed, to decomposeportions of the medium and thus to record the desired data. Suchprinters are extensively used to provide very accurate hard copies ofanalog and digital data and for the high speed production ofalpha-numeric print from computer outputs. As a consequence of thedecomposition or burning away of the electro-sensitive sheet, the styliare subjected to a relatively rapid deposition of residue thereon which,if not removed, results in a fouling of the styli and a consequentdeterioration of the marking process. In addition, because of theelectrical currents carried by the styli and because of the frictionbetween styli and the electro-sensitive medium within which they are incontact, the multiple stylus assembly is subjected to high operatingtemperatures with a resulting abrasion of the stylus tips and anincreased adherence of the residue deposits thereto.

The composiiton of this type of residue accruing from such printeroperation is such that it is extremely difficult to effect a removalthereof from the contacts or stylus tips by conventional cleaningmethods. These prior art methods have included continuous brushing,subjection to air pressure or to vacuum, or a combination thereof, allof which have proved inadequate to permit continuous operation of theprinter over a period of hours. The provisary in effecting sion of anadequate cleaning method is made more difficult by the fact that severalhundred styli may be used in a single printer with the record-markingoperation being performed in proximity to moving or rotating mechanicalparts. In addition, the styli themselves are typically of a verydelicate construction, and thus, added care is necesthe removal of theresidue. Effective cleaning of these delicate parts has ultimatelyrequired a shut-down of printer operation, resulting in a loss ofvaluable time in the recording, for example, of computer output data.Further, additional downtime has been necessary for the periodicadjustment and eventual complete replacement of the stylus assemblies asa consequence of wear during the high temperature operation to whichthey are subjected.

In accordance with the present invention, there is provided apparatusand method by which styli or other electrical contacts which aresubjected to deleterious contamination by residue and to hightemperature operation may be cyclically cleaned and cooled while inoperation without impairing or interfering with the operation ofadjacent mechanisms or with the marking and recording operation itself.The styli are alternately subjected to timed blasts of cooling air andof non-abrasive impact material. An automatic brushing operationperformed simultaneously with the impact cleaning operation removes thecontaminating residue and any impact material particles which maymomentarily lodge between the contacts. The dislodged deposits arerapidly and continuously collected and removed from the stylus area by ascavenger exhaust system to prevent any subsequent refouling of thestyli and/or interference with associated moving mechanisms, or with therecording operation.

In the following description of an exemplary embodiment and itsoperation, the term impact material is used as opposed to abrasives.Abrasives are generally considered to be harder than the material withwhich they come in contact and therefore ultimately result in a cuttingor wearing away of the material which is to be cleaned. The impactmaterial used in conjunction with the present invention is relativelysoft, and cleaning is effected from the force of the impact rather thanfrom the abrasive nature of the cleaner. The impact cleaning feature isalso important in view of the fact that the contacts or styli may belocated adjacent rotating and moving machinery parts which wouldnormally be damaged by the harder abrasives.

Other significant features of the present invention include a mixernozzle to lift impact material from a supply bin by creation of avacuum, and to mix this materiel with an air stream; a distributionmanifold which precisely and separately meters and directs first coolingair and then the air-impact material mixture, or vice versa, upon themultiple stylus assembly; a scavenger exhaust system for immediatecollection and removal of the impact cleaning material and dislodgedresidue from the stylus marking area.

It is, accordingly, a principal object of the present invention toprovide improved apparatus and method for cleaning electrical contactassemblies.

It is a further object of the present invention to clean and coolelectrical contacts by the cyclic application thereto of blasts ofimpact material and cooling air.

Another object of the present invention is to prevent faulty operationof electro-sensitive printers and recorders by removal of residuebuild-up and by reduction of high temperatures in the multiple stylusassemblies thereof.

It is a still further object of the present invention to clean multiplestylus assemblies while the printer or recorder is in operation, withoutthe requirement of downtime.

It is another object of the present invention to provide substantiallycontinuous cooling of the styli or contacts to reduce adhesion of thedecomposition products of the recording operation and thereby to reducethe duration and frequency of the impact cleaning cycle.

Another object of the present invention is to remove used cleaningmaterial and dislodged residue from the locality of the contacts and todeposit such materials in a remote area for convenient disposal.

Other objects, features and attendant advantages of the presentinvention will become apparent from a consideration of the followingdetailed description of certain exemplary embodiments, especially whentaken in conjunction with the accompanying drawings in which:

FIGURE 1 is a perspective view, partially in electromechanical schematicform, of a complete cyclic cleaning and cooling system in accordancewith the present invention;

FIGURE 2 is a perspective view of a portion of the system used in theimpact cleaning cycle operation;

FIGURE 3 is a portion of the system used in the air cooling cycleoperation;

FIGURE 4 is a partial view of the distribution manifold, mixer nozzles,impact material secondary hopper, and scavenger exhaust system;

FIGURE 5 is a detail perspective view, partially broken away, of thedistribution manifold; and

FIGURE 6 is a detailed perspective view, partially broken away andpartially in section, of the mixer nozzle.

Referring generally to the drawings, and more particularly to FIGURE 1,a compressor and heat exchanger, designated generally at 10, forsupplying cool, dry air under pressure, are coupled by a flow line 12through a suitable line filter 13 and pressure regulator 14 to a pair ofair valves 15 and 16. The valves are solenoid operated, under thecontrol of time and function sequence apparatus designated generally at18, electrical power being supplied through suitable connecting cables19 and 20. Air flow through the valves and supply lines 25 and 26 isregulated by pressure regulators 22 and 23, respectively. The air flowthrough supply lines 25 and 26 is cyclic, as will hereinafter beexplained, to provide sequentially alternating air streams to thedistribution manifold, designated generally at 33, and to mixer nozzles34. Impact cleaning material is supplied from main hopper or bin 30, viaa gravity feed line 27, to a secondary hopper or set of hoppers 31 andsubsequently to the mixer nozzles via secondary feed lines 28.

The scavenger exhaust system includes a hooded exhaust manifold 35,removal duct 36, and exhaust turbine 39. A motor 37 is used to rotate aspiral brush 121 (FIGURE 4) against the styli 90 adjacent the exhaustmanifold. Suitable pressure indicators 41, 42, 43, 44 may be employed toindicate air pressures in supply lines 12, 25, 26 and the exhaust vacuumin duct 36, respectively. In addition, it may be desired to providealarm indicators, as for example pressure indicator light 46, vacuumindicator light 47, and impact material light 48, electrically connectedto the detectors and to an audible alarm 49. Such apparatus provides anindication of one or more critical conditions existing in the variousportions of the system. The impact material indicator light 48, forexample, may be controlled by a low level switch 50, in the main hopper30, to indicate the need for additional impact material.

Operation of the system will be better understood by consideration ofFIGURES 1, 2, 3 and 4. The timing sequence of the overall operation maybe established by use of a timer 101, driving a series of cam operatedswitches, 102, 103, 104, 105, 106 and 107. Each cam is arranged tooperate its associated switch at precise intervals and in accordancewith rotation of the shaft to which the cams are connected. As anexample, timer 101 may be set to operate at a speed of 0.1 r.p.m. whilethe cam operated switches are set to operate at intervals of one to tenminutes. Thus, any particular time interval within the prescribed limitsmay be selected by operation of one of switches 110. Power is suppliedto timer 101 via switch 112, through cable 113, during the time thetransport carrying the electro-sensitive sheet is in motion.

The timing sequence apparatus in turn controls the frequency at whichthe function sequence occurs. A second timer 115 drives a series of camoperated switches 118, 119 and 120, for example, to effect the cyclicopening and closing of valves 15 and 16, as well as to operateappropriate detection apparatus to indicate that operation is proceedingin a proper manner. Cam operated switch 118, when cyclically opened andclosed, permits power to be supplied to the solenoids in air valves 15and 16, thus causing them to be energized and de-energized. One of thevalves, for example 15, may be set for a normally open condition, whilethe other is set for a normally closed position, such that energizationand deenergization of the solenoids will produce a cyclic operation ofthe valves, one valve alternating between closed and open conditionwhile the other alternate respectively between open and closedcondition.

Cyclic operation of the system will be more clearly understood byreference to FIGURES 2 and 3. An alternative valve control arrangementis shown in these figures, although the system otherwise operates asindicated in the description of FIGURE 1. A time 60 rotates a pair ofearns 61 and 62, associated respectively with valves 16 and 15 to openand close the valves. A counter 63 may be used to record the number ofcyclic operations occurring in a given period. While the controlarrangement depicted in FIGURE 2 does not have the time and functionsequence features of the control arrangement of FIGURE 1, it is adequateto provide the desired cyclic operation. It will, of course, beunderstood that various other electrical and mechanical devices or acombination thereof may be employed to control the air valves.Electronic time delay circuits, for example, may be employed in place ofthe switching control arrangement shown in FIGURE 1. The cams shown inFIGURE 2 have rotated through a position in which valve 16 is open andvalve 15 is closed. Pressurized cool air is thus permitted to flow fromsupply line 12 through valve 16 and into supply line 26, from which itis fed through lines 65 to mixer nozzles 34. Each mixer nozzle isarranged to create a vacuum therein, as will be explained with referenceto FIGURE 6, such that impact cleaning material is lifted from thesecondary hopper 31 to feed lines 28 and thus up into the nozzle whereit mixes with the air stream. In this manner, a mixture of forced airand cleaning particles is directed through the distribution manifold toimpinge upon the styli.

In FIGURE 3, the system is in the cooling cycle condition since cam 61has disengaged and cam 62 has engaged through rotation of the shaftcoupled to timer 60. Thus, air valve 16 closes as valve 15 is opened. Inthis condition, the cooling air flows from supply line 21 through valve15 and into line 25, where it is directed through distribution manifold33. The air stream is expelled from the distribution manifold in anappropriate pattern to cool the styli.

Examples of the construction of the mixer nozzle and the distributionmanifold are shown in FIGURES 6 and 5 respectively. Nozzle 34 hasassociated therewith an inlet 75 through which an air stream or flow isdirected from supply line 65 at a suitable pressure, for example 60 topsi. A second inlet 76, connected to the nozzle through a T junctionpermits the introduction of impact material. The air stream is expelledfrom a nozzle 77, at relatively high velocity. Chamber 78 surrounds theduct between inlet 75 and nozzle 77 to the point of connection of theimpact material feed line 28. As the high velocity stream passes fromnozzle 77 through chamber 78, it impinges on air in the chamber andcarries it away, creating a vacuum therein for sucking cleaning materialinto the mixer nozzle from the feed lines. The impact cleaning materialis granular in form and of a sufficiently fine mesh and a low density tobe lifted by a combination of the vacuum created in chamber 78 and theturbulence of the air in secondary hopper 31, the latter also caused bythe passage of the air stream through nozzle 77 into the chamber. Theimpact cleaning material is thus mixed with the air stream in thechamber and expelled through orifice 79.

The vacuum action of mixer nozzle 34 eliminates the need for a separatecontrol valve and air line to force the impact material from a storagebin and thus reduces Wear to a minimum. In addition, the use of a vacuumas an impact material lifter also eliminates packing in the secondarybin and possible consequent clogging of the transfer line. Further, therate of flow of impact material may be adjusted within desired limits bysimply adjusting the air pressure feeding into the mixer nozzle throughregulator 23. Typically, air or other fluid carrier fed into the nozzleat inlet 75 will be adjusted to a pressure between 60 to 100 p.s.i.

Exemplary details of construction of the distribution manifold areillustrated in FIGURE 5. Each manifold has a pair of inlets 80 and 81and a pair of chambers 83 and 84, separated from each other by a wall85. The chambers are provided with a triangular cross-section suitablefor alternately directing the flow of the air-impact material mixtureand cooling air toward the narrowly defined area occupied by the styli.To this end, a pair of orifices for each chamber are separated by Wall85 to provide exits for the cooling air and cleaning mixture. The airchamber orifice may comprise a row of apertures, while the mixturechamber depicted for the orifice is preferably of a slotted shape. Thatportion of the mixer nozzle 34 including orifice 79 is arranged to fitinto inlet 80 such that it extends into chamber 83- (FIGURE 4).

The dual chamber construction of the manifold permits dry cooling air tobe directed in a stream over the contacts or styli during one portion ofthe cycle and the impact cleaning mixture to be directed toward thecontacts or styli during the other portion of the cycle withoutinterference therebetween. That is, the manifold construction insuresthat no impact material will be distributed during the cooling cycle.The mixture chamber 83 has a shape arranged to produce minimuminterference with the mixture flow expelled from the mixer orifice 79.The latter may be constructed to provide maximum distribution of impactmaterial over the widest range of air pressures. For example, anappropriate fan-shaped distribution of approximately 4.4 grams persecond of impact cleaning material was produced with a mixer nozzlehaving a nozzle opening 77 of .126 inch, orifice 79 width of .045 inch,and manifold orifice 88 of approximately .070 inch. Each of the figureswhich has been described shows a three unit nozzle and manifold system,but it will be understood that any number of units may be employed asnecessary for a particular application.

The combination of impact material hopper 31, mixer nozzles 34, supplylines, distribution manifolds 33, and exhaust system is illustrated ingreater detail in FIGURE 4. Granular impact cleaning material, generallydesignated at 126, is supplied to the secondary storage bins 31 bygravity feed from the main hopper or bin 30. The angle of repose, 0, ofeach of the slanted sections of flooring of the secondary bins 31 isselected to maintain a sufficient supply of impact material aroundsuction feed line 28 to nozzle 34 without permitting undue packingdensity.

The cleaning material is selected in accordance with the requirementsthat 1) it should not cause abrasive wear in the rotating parts of themachine in which it may come in contact; (2) it should not abrade thestylus material or the distribution nozles; (3) it must beofsufficiently low density to be lifted into the nozzle without cloggingand to be carried away by the scavenging exhaust system; (4) it must besutficiently strong and hard to remove residue from the stylus tips uponhigh velocity impact; (5) it must be of a sufficiently fine mesh to passbetween the styli, but should not be dusty; and (6) it must be low incost and readily available. Silica and most of the other oxidesavailable in appropriate mesh sizes have been found to be too abrasivefor the cleaning of delicate electrical elements adjacent rotatingmachinery. Crushed walnut shells of to mesh are exemplary of materialsmeeting the above requirements for use as the impact material. Othersuitable materials are various types of crushed nut shells or groundfruit pits, such as ground apricot pits, provided that appropriateadjustments are made in the air pressure regulators in accordance withdensity, weight and mesh of the particular material used.

During the cleaning cycle, the impact particles are lifted from thesecondary bins 31 under suction in feed lines 28, and mixed with the airstream from lines 65 in mixer nozzle 34 in the previously describedmanner. The mixture of air and cleaning material is then directedthrough the orifice slot 79 from chamber 78 in a fan-shaped pattern.Construction of distribution manifolds 33 permits metering of the properamount of the mixture to impinge upon the stylus tips, generallydesignated at 90, while maintaining the flow pattern. A rotating spiralbrush 121 is mounted on the shaft 120 driven by motor 37 (FIG- URE l) toaid in dislodging residue and any cleaning material which maytemporarily lodge on the stylus tips. This debris is immediatelycollected in the scavenger exhaust manifold 35, by virtue of the vacuumcreated in duct 36, to prevent its being blown about the work area. Tothis end, suflicient velocity is imparted to the materials by turbine 39in the exhaust line to effect their efiicient collection and removal toa suitable area for subsequent dis posal. While FIGURE 4 convenientlyillustrates both the flow of air during the cooling cycle and the flowof the air-impact material mixture during the clean ing cycle, it willbe understood that these operations Will occur alternately rather thansimultaneously.

It is also again to be emphasized that while throughout thisspecification reference has been made to use with multiple stylusassemblies in electro-sensitive writing processes, systems in accordancewith the present invention may be readily used in conjunction with thecleaning of other types of electrical contact assemblies which may besubjected to contamination by residue from any source. It will furtherbe realized that various fluids, including gases in the broad sense, maybe used in place of air.

Thus, while certain preferred embodiments have been illustrated anddescribed, it will be apparent that various changes and modificationsmay be made without departing from the true spirit and scope of thepresent invention. It is therefore desired that this invention belimited only by the appended claims.

I claim:

1. Apparatus for cleaning electrical contacts, comprismg distributionmanifold means for distributing streams of non-conductive fluid over andonto the contacts to be cleaned, each said manifold means including apair of separated chambers and a respective orifice associated with eachchamber;

storage means for holding particulate material;

a mixer nozzle communicating with one of said chambers;

a supply line coupling said mixer nozzle to said storage means, saidmixer nozzle and said storage means being relatively located to preventgravity feed of said particulate material into said mixer nozzle;

means for supplying fluid under pressure to said mixer nozzle to producea vacuum condition tending to suck particulate material from saidstorage means via said supply line into said mixer nozzle, said mixernozzle including means for mixing said particulate matter into saidfluid for ejection of a particle-containing fluid stream from saidnozzle into said chamber of said manifold means with which said mixernozzle communicates;

power actuated brush means for rotation against said contacts todislodge debris from said contacts during distribution of saidparticle-containing fluid stream over and onto said contacts by saidmanifold means;

means for supplying fluid under pressure directly to the other of saidchambers of said manifold means for distribution of a pure fluid streamover and onto said contacts therefrom;

means for operating the first-named and last-named fluid supply means inalternation for cyclic alternating distribution of saidparticle-containing and pure fluid streams over and onto said contacts;and

vacuuming exhaust means having an inlet positioned relatively oppositesaid orifices of said manifold means, with said contacts substantiallyinterposed therebetween, for collecting said particulate materialfollowing impact with said contacts and for collectticulate material isrelatively non-abrasive.

3. The invention according to claim 1 wherein said fluid is air.

References Cited UNITED STATES PATENTS 2,257,144 9/1941 Worsham 5182,612,731 10/ 1952 Gladfelter et a1 51-8 2,729,917 1/1956 Gregory 51--82,907,200 10/1959 Roberts et al 51-8 X 2,846,820 8/1958 Persak et al.518 3,139,704 7/ 1964 McCune 51--8 MICHAEL E. ROGERS, Primary Examiner.

US. Cl. X.R.

